Time: 2pm

Location: 2N36

Title: TBA

Abstract: TBA

# Events

Time: 2pm

Location: 2N36

Title: TBA

Abstract: TBA

Time: 2pm

Location: A4

Title: TBA

Abstract: TBA

Time: 2pm

Location: 2N36

Title: TBA

Abstract: TBA

Time: 3pm

Location: 3C4

Title: TBA

Abstract: TBA

Time: 2pm

Location: 2N36

Title: An EFT approach to black hole perturbations in scalar tensor theories

Abstract: In this talk, I will introduce an effective field theory (EFT) for perturbations around spherically symmetric spacetimes with a non-trivial scalar field profile. I will then apply this framework to study quasi-normal modes of static black holes with a scalar hair. I will argue that "hairy'' solutions provide the most minimal yet interesting modifications of the quasi-normal spectrum of Schwarzschild black holes. Assuming that the deviation of the background from Schwarzschild is small, I will use a WKB approximation to introduce the notion of "light ring expansion". This approximation is analogous to the slow-roll expansion used for inflation, and it allows us to express the quasinormal mode spectrum in terms of a small number of model-independent parameters to be constrained by observations. This is the first step towards an EFT framework for placing model-independent constraints on the gravitational sector based on the ringdown phase of gravitational wave events.

Time: 2pm

Location: 2N36

Title: Is it a small world after all? Searching for the shape of the universe

Abstract: We know the average spatial curvature of the universe is very small, but that is just simplest aspect of its large-scale shape. What is the topology of the universe? So far our searches for topology have yielded only limits. But when the search space is multi-dimensional, and the searches are specialized, how constraining are they? Meanwhile there are tantalizing hints in the large-angle anomalies of the cosmic microwave background that they may be signs of non-trivial cosmic topology. We will discuss.

Time: 2pm

Location: 2N36

Title: Generalized Gibbs Ensemble and KdV charges in 2d CFTs

Abstract: 2D CFTs have an infinite set of commuting conserved charges, known as the quantum KdV charges. There is a generalised Gibbs ensemble for these theories where we turn on chemical potentials for these charges. I will describe some partial results on calculating this partition function, both in the limit of large charges and perturbatively in the chemical potentials.

Time: 1pm

Location: 4N12

Title: Black hole microstates form mass deformations in the SYK model

Abstract: We consider the mass deformed SYK model which can escape the interiors of pure boundary state black holes. SYK boundary states are given by a simple local boundary condition on the Majorana fermions and then evolved in Euclidean time in the SYK Hamiltonian. We study the ground state of this mass deformed SYK model in detail. We also use SYK boundary states as a variational approximation to the ground state of the mass deformed SYK model. We compare variational approximation with the exact ground state results and they show good agreement. We also study the time evolution of the mass deformed ground state under the SYK Hamiltonian. We give a gravity interpretation of the mass deformed ground state and its time evolutions. In gravity side, mass deformation gives a way to prepare black hole microstates that are similar to pure boundary state black holes. Escaping protocol on these ground states simply gives a global AdS2 with an IR end of the world brane. We also study the thermodynamics and quantum chaotic properties of this mass deformed SYK model. Interestingly, we do not observe the Hawking Page like phase transition in this model in spite of similarity of the Hamiltonian with eternal traversable wormhole model where we have the phase transition.

Time: 3pm

Location: 3C4

Title: Higgs EFTs and the Geometry of EWSB

Abstract: Effective field theories of the Higgs boson not only allow for the sensible interpretation of Higgs coupling measurements, but also optimize the development of experimental analyses. Since the discovery of the Higgs, tremendous progress has been made in formulating suitable Higgs EFTs and exploring their properties. In this talk, I’ll highlight novel theoretical aspects of the prevailing Higgs EFT (the ``Standard Model EFT’') and their experimental implications for Higgs measurements at the LHC. I’ll then explore the limitations of this approach, presenting universal geometric criteria for determining the appropriate EFT for the Higgs sector and illustrating how LHC measurements can probe the geometry of electroweak symmetry breaking.

Time: 2pm

Location: 2N36

Title: Anomaly inflow, geometric engineering, and holography

Abstract: A large class of 4d SCFTs can be engineered by wrapping a stack of M5-branes on a compact space, possibly with defects. ‘t Hooft anomalies are crucial observables for such theories, which often do not admit any known Lagrangian description. Building on the seminal work of Freed, Harvey, Minasian, Moore, we develop systematic tools for extracting the ‘t Hooft anomalies of a geometrically engineered 4d theory using anomaly inflow from the M-theory bulk. We exemplify our tools by studying a class of setups with M5-branes probing a C^2/Z_2 singularity. We argue that these setups define 4d SCFTs which are dual to a class of AdS_5 solutions—first discussed by Gauntlett, Martelli, Sparks, Waldram—whose field theory interpretation has been a longstanding puzzle.

Time: 2pm

Location: 2N36

Title: Correlators of BPS lines in conformal field theory

Abstract: We study the properties of correlation functions of conformal line operators in four-dimensional superconformal field theories. These are treated as n-point functions on the configuration space of conformal line operators. An especially simple set of these correlators are those of BPS line operators which are annihilated by an appropriate subset of the supercharges. Perhaps surprisingly, their topological properties are sensitive to the signature of the space-time metric and to the signature the line operators.

Time: 2pm

Location: 2N36

Title: Perturbative unitarity in Kaluza-Klein theories

Abstract: Scattering amplitudes of massive spin-2 particles generically grow with energy and lead to violations of perturbative unitarity. One way to partially soften such amplitudes is with the infinite towers of particles present in Kaluza-Klein theories. In this talk I will discuss in detail this mechanism of unitarization for general dimensional reductions of pure gravity and show that it leads to some interesting constraints on the eigenfunctions and eigenvalues of the scalar Laplacian on closed manifolds. A consequence of these constraints is that there exists an upper bound on the gaps between Kaluza-Klein excitations of the graviton, which applies also to Calabi-Yau compactifications of string theory.

Time: 2pm

Location: 2N36

Title: The Hubble Hullabaloo

Abstract: As the cosmological dataset has become more precise, some cracks in the concordance model of cosmology have appeared. Using the standard LCDM model, measurements of the CMB can infer the current Hubble parameter to a high precision. This value differs significantly from that measured using a local distance ladder and supernovae. I will review aspects of this tension and present ideas proposed to solve the tension. Future observations of neutron star mergers are expected to provide independent and precise measurements of the Hubble parameter.

Time: 2pm

Location: 2N36

Title: From Wilson to Lindblad: Late-time Obstacles to Reliable EFT Calculations with Horizons (and how Open EFTs can help)

Abstract: Precision calculations in de Sitter space (such as of inflationary predictions for primordial fluctuations) are often plagued by infrared problems and issues of secular time dependence. Similar issues about the breakdown of perturbation theory seem also to arise for information loss in black holes. This talk briefly summarizes how related problems can arise in other areas of physics, and how they are dealt with there when they do. It is argued that Master-Equation/Lindblad techniques used in areas like optics also apply to cosmology (and possibly black holes) and can tell us how to extract reliably late-time predictions. Applied to inflation they lead to Starobinsky's stochastic methods, plus small but important corrections, and this explains why stochastic inflation seems to resum IR effects in simple examples. It allows these tools to be generalized to apply more broadly. This talk describes a simple illustrative application to a qubit in Rindler space (ie an Unruh observer), where they correct earlier results by Candelas and Sciama and show in detail how and why these techniques work.

Time: 2pm

Location: 2N36

Title: Bootstrapping Inflationary Correlators

Abstract: The central idea of the bootstrap philosophy is to constrain observables directly from consistency conditions alone, bypassing the intricacies of the Lagrangian formalism and Feynman diagrams. In this talk, I will adopt this viewpoint and describe a new approach to determine cosmological correlators, following a perspective familiar from the modern studies of scattering amplitudes. Specifically, I will describe the symmetries and singularities of correlators in slow-roll inflation, and explain how these principles can be used to fully determine the final answer without reference to bulk time evolution.

Time: 3pm

Location: A4

Title: Looking for More New Physics in Long-Baseline Oscillation Experiments

Abstract: Over the last couple of decades we discovered and started exploring the phenomenon of neutrino flavor oscillations. These revealed that neutrinos have nonzero masses and leptons mix. Many questions remain and many of them can only be realistically addressed with long-baseline neutrino oscillation experiments. Here, I will review what are these questions and will emphasize that they go beyond the search for CP-invariance violation in the lepton sector and precision measurements of the neutrino oscillation parameters - the main purpose of next-generation long-baseline experiments is to test whether our current understanding of the neutrino sector is not just adequate but also complete. I will discuss a few possibilities for what "other" new phenomena could be lurking in the neutrino-sector and will discuss a few case-studies that illustrate the reach of near-future experiments like DUNE and Hyper-Kamiokande.

Time: 11am

Location: 4N12

Title: Is the scattering amplitude analytic in a field theory with compact space coordinate?

Abstract: It is now accepted that theories in D>4 play an important role in our efforts to unify fundamental forces. At low energies the extra spatial dimensions must be compactified to describe physics experiments in accessible energies. There are models where the radius of compact dimensions could be large. The phenomenology has been studied. Khuri examined analytcity properties of scattering amplitude in a nonrelativistic potential model with a compact dimension and showed that the amplitude in nonanalytic. If such behavior persists in relatvistic QFT there will be serious problem. We address this issue.

Time: 11am

Location: 4N12

Title: Massive Gravitons in Curved Spacetimes

Abstract: This talk will cover various interesting topics that occur in massive spin-2 on various spacetimes including de Sitter, anti-de Sitter, and flat space. In de Sitter, we examine what happens to massive gravity as its mass approaches the partially massless value. In this limit, if the interactions are chosen to be precisely those of the 'candidate' non-linear partially massless theory, the strong coupling scale is raised, giving the theory a wider range of applicability. In anti-de Sitter and flat spacetime, we show how shift symmetries acting on the vector modes emerge from massive spin-2 theories fixing the non-linear structure and discuss whether these theories have amplitudes that can be constructed via soft subtracted recursion.

Time: 2pm

Location: 2N36

Title: Dark Matter Targets with Exponentially Small Couplings